C 個人筆記

char 陣列

string str1= "hello.";

string str2=str1; // 沒有問題
char chararr[20] = "hello.";
char chararr1[20];
chararr1 = chararr；//如果直接將chararr賦值給chararr1是會報錯的
//char陣列賦值1、mencpy； 2、strcpy 推薦用第二個
//1、memcpy
memset(chararr1, 0, 20);
memcpy(chararr1, chararr, strlen(chararr)); //必須先呼叫menset 否則 chararr1中會有部分是亂碼
//2、strcpy
strcpy(chararr1, chararr); //這裡可能會報錯error c4996: 'strcpy' 請參考

//64位系統中個型別的位數

int ishort = sizeof(short);
int ishort1 = sizeof(short int); 
int i = sizeof(int); 
int ilongi = sizeof(long int);
int ilong = sizeof(long);
int illong = sizeof(long long);
int idouble = sizeof(double);
int ifloat = sizeof(float);
int ichar = sizeof(char);
int iusingint = sizeof(unsigned int);
cout << "short:" << ishort << endl << "short int:" << ishort1 << endl;
cout << "int:" << i << endl << "long int:" << ilongi << endl;
cout << "long:" << ilong << endl << "long long:" << illong << endl;
cout << "double:" << idouble << endl << "float:" << ifloat << endl;
cout << "char:" << ichar << endl << "unsigned int:" << iusingint << endl;

short:2

short int:2
int:4
long int:4
long:4
long long:8
double:8
float:4
char:1
unsigned int:4

string str = "heloo.";

cout <<"strlen(str):" << strlen(str.c_str())<< endl << "size():" <